Automatic switch controllers are now available for applying power to lighting in response to external stimuli, for example, motion activity within a defined area, or rise/fall of outside ambient light level. In interior lighting applications, automatic switch controllers have an infrared thermal energy sensor for automatically switching off the lighting in the absence of motion activity over a predetermined period of time after everyone has left the controlled area. It will be appreciated. that considerable energy savings may be realized by automatically turning off interior lighting when the room is not occupied.
Automatic lighting control units which include a motion sensor provide the desired control flexibility to accommodate irregular working hours, and make lighting available for a controlled area as long as motion activity of any kind is sensed within a predetermined time interval. Such automatic control units are wire-for-wire replaceable with standard ON/OFF switches, with the operating power for the controller being derived from the hot conductor of an AC power distribution system.